linux-kernel - Re: [PATCH v6 1/2] dt-bindings: edac: arm-dmc520.txt

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Date:   Fri, 1 Nov 2019 14:30:15 -0700
From:   Lei Wang <wangglei@...il.com>
To:     Lei Wang <wangglei@...il.com>, Rob Herring <robh+dt@...nel.org>
Cc:     "bp@...en8.de" <bp@...en8.de>,
        "james.morse@....com" <james.morse@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "hangl@...rosoft.com" <hangl@...rosoft.com>,
        "lewan@...rosoft.com" <lewan@...rosoft.com>,
        "ruizhao@...rosoft.com" <ruizhao@...rosoft.com>,
        "scott.branden@...adcom.com" <scott.branden@...adcom.com>,
        "yuqing.shen@...adcom.com" <yuqing.shen@...adcom.com>,
        "ray.jui@...adcom.com" <ray.jui@...adcom.com>, shji@...rosoft.com
Subject: Re: [PATCH v6 1/2] dt-bindings: edac: arm-dmc520.txt

Hi Rob,

Kindly ping... I addressed your comments in below, and with one 
question. Thanks!

-Lei

On 10/25/19 10:31 AM, Lei Wang wrote:
> Thanks James/Rob/Borislav for pointing out the email list issue. My work 
> email does not work good either for this exercise. Going forward I'll 
> switch to my gmail account.
> 
> And Thanks Rob for reviewing! Please see below.
> 
>>> +++ b/Documentation/devicetree/bindings/edac/arm-dmc520.txt
>>> @@ -0,0 +1,26 @@
>>> +* ARM DMC-520 EDAC node
>>> +
>>> +Required properties:
>>> +- compatible           : "brcm,dmc-520", "arm,dmc-520".
>>> +- reg                  : Address range of the DMC-520 registers.
>>> +- interrupts           : DMC-520 interrupt numbers. The example 
>>> below specifies
>>> +                         two interrupt lines for dram_ecc_errc_int and
>>> +                         dram_ecc_errd_int.
>>> +- interrupt-config     : This is an array of interrupt masks. For 
>>> each of the
>>
>> Not a standard property, so would need a vendor prefix...
> 
> Would dmc-interrupt-config as the property name work? Thanks!
> 
>>
>>> +                         above interrupt line, add one interrupt 
>>> mask element to
>>> +                         it. That is, there is a 1:1 mapping from 
>>> each interrupt
>>> +                         line to an interrupt mask. An interrupt 
>>> mask can represent
>>> +                         multiple interrupts being enabled. Refer to 
>>> interrupt_control
>>> +                         register in DMC-520 TRM for interrupt 
>>> mapping. In the example
>>> +                         below, the interrupt configuration enables 
>>> dram_ecc_errc_int
>>> +                         and dram_ecc_errd_int. And each interrupt 
>>> is connected to
>>> +                         a separate interrupt line.
>>
>> I've gone and read thru the TRM some. This binding doesn't seem to
>> correspond to the TRM at all. There are a bunch of interrupts and a
>> combined interrupt, and then there's the same set for 'overflow'
>> interrupts.
>>
>> There's only one 'interrupt_control' reg. How do you have more that 1
>> 32-bit value?
> 
> There is only one 'interrupt_control' register, for multiple interrupt 
> sources. Then depending on platform hardware design, these interrupt 
> sources can be wired to different physical interrupt lines.
> 
> That is, it is possible to mux interrupt sources into  interrupt lines 
> for dmc520 in different ways. For example, in this particular brcm 
> implementation,
> 
> Line 841: source dram_ecc_errc_int
> Line 843: source dram_ecc_errd_int
> Line 839: source dram_ecc_errc_int and dram_ecc_errd_int
> 
> There are two possibilities for implementing ecc counts for ce/ue. And 
> we chose to use the single source line: as below, two interrupt lines 
> 0x349 and 0x34B, with interrupt masks 0x4 and 0x8 respectively.
> 
> Also, it's possible to implement using the combined-source line too: 
> that would be one interrupt line 0x347, with interrupt mask 0xC.
> 
> This dt binding can support both by modifying the properties, without 
> having to modify driver code.
> 
>  >> +
>  >> +Example:
>  >> +
>  >> +dmc0: dmc@...000 {
>  >> +       compatible = "brcm,dmc-520", "arm,dmc-520";
>  >> +       reg = <0x200000 0x80000>;
>  >> +       interrupts = <0x0 0x349 0x4>, <0x0 0x34B 0x4>;
>  >> +       interrupt-config = <0x4>, <0x8>;
>  >> +};
>  >> --
>  >> 2.17.1
> 
> Thanks!
> 
> -Lei
>